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Fantastic Tales of Super Ceramics

Fantastic Tales of Super Ceramics. Professor M. L. Mecartney Department of Chemical Engineering and Materials Science University of California, Irvine. Ph.D. Students Peter Dillon Tiandan Chen Sungrok Bang Lynher Ramirez M.S. Students Kevin Olson. Undergraduate Students

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Fantastic Tales of Super Ceramics

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  1. Fantastic Tales of Super Ceramics Professor M. L. Mecartney Department of Chemical Engineering and Materials Science University of California, Irvine

  2. Ph.D. Students Peter Dillon Tiandan Chen Sungrok Bang Lynher Ramirez M.S. Students Kevin Olson Undergraduate Students Daniel Strickland (NSF REU) Joy Trujillo (UC LEADS) Jeremy Roth (SURP) External Collaborators Professor Trudy Kriven, University of Illinois Professor Susan Krumdieck, University of Canterbury, NZ My Research Group

  3. How I found ceramic science, and discovered a life I was once a lowly Classics major, studying Greek and Latin at Case Western Reserve University…. Then I discovered Materials Science and Engineering – Solid State Physics and Physical Chemistry!!! Undergraduate research on positron annihilation in alumina (in Physics) and single crystal deformation of ZrO2 (in MSE)

  4. Post B.S./B.A. Wanderings Graduate school – M.S. and Ph.D. in Materials Science and Engineering at Stanford University (BaTiO3 and Si3N4) Post-doctoral research – Max-Plank-Institut in Stuttgart, Germany (ZrO2) Faculty positions – University of Minnesota, Minneapolis, then University of California, Irvine (LiNbO3, Pb(Zr,Ti)O3, V2O5, CaO-B2O3-SiO2, (Sr,Ba)Nb2O6, etc.)

  5. Fantastic Ceramics • Did you know that ceramic conductors are a critical part of fuel cell technology? • Did you know that ceramics can be stronger than any other material? • Did you know that ceramics can be deformed just like metals? • Did you know that ceramics can conduct electricity without any resistance?

  6. Super Ceramics • Super ionic conductors for fuel cells • Super strong ceramics for cutting applications • Super plastic ceramics for net shape forming • NO CERAMIC SUPERCONDUCTORS IN THIS TALK

  7. CERAMICS • A ceramic is a compound composed of at least one metallic and non-metallic element • Ionic/covalent bonding

  8. Most Ceramics are Crystalline ZrO2 NaCl

  9. Typical Grain / Grain Boundary Structure H.L. Tuller: “Ionic conduction in nanocyrstalline materials.” Solid State Ionics146, 157 (2000).

  10. Ceramics as Ionic Conductors

  11. Brick Layer Model Polycrystalline Material Model Equivalent Circuit Model Modified From S M. Haile, D L West, and J. Campbell, J .Mater. Res. vol 13, pp.1576-1595 (1998).

  12. AFM of YSZ Film on Al2O3 R.M. Smith, X.D. Zhou, W. Huebner, and H.U. Anderson (2004), "Novel Yttrium-Stabilized Zirconia Polymeric Precursor for the Fabrication of Thin Films," Journal of Materials Research, 19, 2708-2713.

  13. 15X ConductivityIncreasein Nano-crystalline Zirconia! H.L. Tuller: “Ionic conduction in nanocyrstalline materials.” Solid State Ionics146, 157 (2000).

  14. Increase in GB Conductivity X. Guo and Z.L. Zhang (2003), "Grain Size Dependent Grain Boundary Defect Structure: Case of Doped Zirconia," Acta Materialia, 51, 2539-2547.

  15. Propoxide Sol-Gel TF Preparation

  16. Acetate Sol-Gel TF Preparation Adapted From: R.M. Smith, X.D. Zhou, W. Huebner, and H.U. Anderson (2004), "Novel Yttrium-Stabilized Zirconia Polymeric Precursor for the Fabrication of Thin Films," Journal of Materials Research, 19, 2708-2713.

  17. Multiple Spin Coated Layers(Ba-Ti on Si Wafer) M.C. Gust, N.D. Evans, L.A. Momoda, and M.L. Mecartney, "In-Situ Transmission Electron Microscopy Crystallization Studies of Sol-Gel Derived Barium Titanate Thin Films," J. Am. Ceram. Soc. 80 [11] 2828-36 (1997).

  18. Cross Sectional SEM ZrO2 Thin Film on Si Wafer

  19. Typical Grain Size of ZrO2

  20. Burning Questions • Will our nanocrystalline zirconia thin films be a super ionic conductor when compared to zirconia with a larger grain sizes? • And why? • Stay tuned for Daniel Strickland’s talk at the end of the summer!

  21. High Strength Ceramics

  22. 50%Al2O3-25%NiAl2O4-25%ZrO2

  23. Fine Grain Ceramics Are Strong, But… • At high temperatures, the smaller the grain size, the easier to deform a material (creep). • These materials were developed to be high speed cutting tools, the tips of which may reach 1500°C. • Will creep be a problem????

  24. Compression Test Results

  25. 50% Al2O3-25%NiAl2O4-25%TZP Undeformed Average Grain Size (mm) Al2O3: 0.76 NiAl2O4 : 0.49 TZP: 0.42 50% Al2O3-25%NiAl2O4-25%TZP Deformed at 1425°C Average Grain Size (mm) Al2O3: 1.39 NiAl2O4 : 0.81 TZP: 0.62

  26. Stress Response

  27. Fine Grain Ceramics May be Super Strong at Room Temperature… ….but very deformable and soft at high temperatures.

  28. Superplastic Ceramics

  29. Superplasticity The ability of polycrystalline solids to exhibit greater than 100% elongation in tension, usually at elevated temperatures about 0.5Tm Constitutive Law J.Wakai, Adv. Ceram. Mater., 1986 Where: έ Strain rate Q Activation energy σ Stress Rg Gas constant n Stress exponent T Temperature (K) d Grain size p Grain size exponent

  30. Applications • SPF enables net-shape-forming, fabricate unique complex shapes from a single piece of materials; • Eliminates parts and process steps, minimizes manufacturing cost. • Ceramic knives are made by superplastic forming in Japan. Examples Y-TZP @1450℃ Kyocera Ceramic Knife

  31. Superplastic Deformation Sudhir, Chokshi, J.Am.Ceram.Soc., 2001 Grain boundary sliding

  32. Simulation of Grain Boundary Sliding during deformation

  33. Grain Size 8Y-CSZ Sintered 2 hours at 1600ºC 3 wt% SiO2, d=1.7µm 0% SiO2, d=10.2µm 1 wt% SiO2, d=2.8µm 5 wt% SiO2, d= 1.6µm 10 wt% SiO2, d=1.2µm

  34. A Superplastic Ceramic8 mol% Y2O3 Cubic Stabilized ZrO2 + 5 wt.% SiO2

  35. Optimal Microstructure for Superplasticity • The smaller the grain size, the easier to achieve superplastic deformation. • But during high temperature deformation, grains grow to minimize grain boundary interfacial area. • Need to design a material in which grain growth is limited.

  36. How to Create a Stable Fine Grain Structure at High Temperatures Grain growth is rapid in single phase materials, slower in two phase materials (zirconia – silica), but should be very limited in a three-phase microstructure Two-phase structure Three-phase structure

  37. II. Experimental Approach 3Al2O3 + 2SiO2 = 3Al2O3•2SiO2 Multiphase ceramic Alumina – Zirconia – Mullite ZrO2 (26nm) Al2O3 (40nm) SiO2 Sol (15nm) Ball Milling Dry, Sieve and Press Sintered at 1450℃ Compressive Deformation XRD, SEM, TEM EDS Analysis

  38. Nanocrystalline Ceramic with Alumina, Mullite, Zirconia SEM of AZ30M30

  39. Deformation Behavior Steady-state deformation of AZ30M30 High strain rate of AZ30M30

  40. Dislocations generated during deformation AZ30M30 Deformed Mullite Grain

  41. Conclusions 1. Nanocrystalline/fine grain ceramics may be superior ionic conductors (increased efficiency for fuel cells). 2. Nanocrystalline/fine grain ceramics have superior strength at room temperature. 3. Nanocrystalline/fine grain ceramics behave like metals at high temperatures, but this may be useful for superplastic forming.

  42. Thanks to the Following for Research Support • NSF Division of Materials Research • National Fuel Cell Research Center • NSF REU program • UCI SURP program • UC LEADS program • Pacific Nanotechnology • Corona Naval Base

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